Project Summary Proper neural networks rely on the neurons' ability to generate neurites (axons and dendrites) and form synaptic connections with appropriate partners. Impairments in neuronal morphology and synapse composition in specific subtypes of neurons have been described in various mental health conditions, ranging from schizophrenia and bipolar disorder to autism spectrum disorder (ASD). Such altered neuronal morphology and synapse assembly presumably underlie disrupted neural circuit function, and therefore disrupted behavioral patterns. The objective of Project 4 is to create a suite of cellular imaging-based assays in hIPSC-derived cultures of differentiated neurons. These assays are based on quantitative fluorescence microscopy, and will focus on specific aspects of neuritogenesis and synaptogenesis that are relevant to ASD. The assays will be compatible with high-content screening technology, and will be applied to engineered hIPSC ASD models.